Wobble plate pump



Patented Dec. 28, 1948 caries My invention relates to pumps and more particularly to a wobble plate pump of compact design.

It is an object of my invention to produce a wobble plate pump that may be operated at high rotational speeds.

Another object of my invention is to provide a wobble plate pump with reliable but inexpensive valves.

Still another object of my invention is to provide a wobble plate pump having simplified valving and porting.

A further object of the invention is to provide a wobble plate pump with a simple seal against atmospheric pressure.

A still further object is to provide a wobble plate pump with an improved drive mechanism.

Other objects and advantages of my invention will be apparent in the following description and claim considered together with the accompanying drawings, in which:

Fig. 1 is an elevation view in full section of the pump showing the two pistons of the pump; and

Fig. 2 is a sectional view taken along the line lIII of Fig. 1.

The pump has a housing it that may be cast or forged of any suitable metal such as aluminum and that has a plurality of concentric bores therein including a. relief valve bore H, a pump cavity or working bore l2, a high pressure bore l3 and an internally threaded'bore Hi. The housing also has an inlet port it communicating with the pump bore AZ by a passage ll. A pressure or output bore 18 is also formed in the body It and communicates with the relief bore l I through a milled passage I9 and with the pressure bore 83 through a drilled passage 2|.

Placed in the relief valve bore it is a relief valve cage 22 spaced from the bottom oi the bore by a notched rim 23 that is integral with the cage. The cage 22 has stepped sides and an apertured bottom having inturned edges 26 forming a valve seat. An O-ring seal 26 is positioned in an annular shoulder 2'? and seals the cage 22 in the bore H. A valve cup 28 retains a valve pad 29 and the cup and pad are pressed on the seat 2 1 by a compression coil spring 83. When sufficient overload pressure builds up in the bottom of bore it, it forces the relief valve tt-Et on of on the cup member 32 is an annular body memdd. This ball forms a bearing for the wobble plate of the pump. The pedestal 36 is secured to the cup 32 by a nut M on the threaded shank 3i and is secured by a lock washer #32. The shallow cup also holds the relief cage 22 and its seal 2% in place as well as providing the compression for the relief spring 3 I.

Also placed in the pump bore I2 and resting her it having an external flange at and two pump cylinders 36. An O-rillg seal Mia is compressed by the external flange id on the body member 133 in a shoulder 4!! formed by the junction of the bores i2 and i3. Placed over the end of the body member (53 is a flanged cap member at compressing an O-ring seal d8 against an annular shoulder 69, thus sealing of! the high pressure portion of the pump in the pressure bore it. An internal flange El of the cap member telescopes with the inner surface of the annular body member M. An annular nut 52 engages the threads Mia and presses a stress-distributing ring 58 against the cap 45, thus holding the assembly together and in the housing It).

Placed in each pump cylinder $6 is a piston M having a flatted projecting shank 55 and a central bore 5? cutting into the shank 56 and terminating in a conical portion 58 at its other end. A conicalvalve 59 made of rubber-like material rests against the conical surface 58 and is of such size that its outer surface is flush with the adjoining end of the piston lit. Thus the valve 59 also acts as a surface of the piston. A rivet tt passing through each valve 59 is connected to one end of a tension spring 65, the other end of which is secured by a hook t2 spanning the bore 57. The shank 56 of each piston has a double tapered hole 63 therethrough.

The wobble plate unit of the pump includes a wobble stick at having a ball head at on its outer g the piston 54 is at the filled with oil soaked wicking 88 for lubricating the socket Joint. The wobble plate is formed by an annular flange 88 on the inner end of the wobble stick 44. Riveted to the wobble plate 59 are two hardened steel rods 10 and an annular plate II. The riveting operation is performed with the ball 38 (with its pedestal 86 attached) positioned in the socket 68. Since the inside diameter of the annular plate II is less than the diameter of the ball 38, a ball and socket joint is formed that cannot come apart in operation. After the riveting operation the ball and pedestal are secured to the shallow cup 32.

Positioned in valve cages I2 in the cap member 45 are compression springs 55 that hold a head valve cap 13 and its pad 13a against the ends of the cylinders 48. The head valve therefore "seals ofl high pressure fluid from entering the pump cylinders 46. The head valves are lifted from their seats when the fluid being compressed by the piston 54 is of sufficient pressure to overcome the spring and the back pressure, and fluid is thus pumped from the intake IE to the high pressure region of bore l3, from whence it may flow through the passage 2| to the outlet l8.

The intake portion of the pump is sealed from atmosphere by a. flexible seal tube 80 having a head 8| on one end locked against an internal flange 82 on the annular body member 48 by the telescoping action of the cap flange The other end of the seal tube is turned inside the rest of the tube and its head 83 is secured against a shoulder 84 on the wobble stick by a snap ring 85 positioned by a groove 86 in the wobble stick 84. The head 8| also serves as a seal between the cap 4| and the working annulus 54.

The wobble stick 64 is gyrated about the ball 38 by a driving wheel 15 mounted on a shaft 16 which may be secured to any suitable source of rotary power such as an electric motor. The left face ll of the wheel 15 is finished at an angle that is normal to the axis of the wobble stick 84 at its desired angle of gyration. The face 11 is recessed to receive a ball bearing assembly 18 and the wobble stick head is positioned inside the inner annular race. This construction permits gyrating the wobble stick 64 without imparting any torsional forces thereto and without giving rise to any frictional forces at the wobble stick head.

The operation of the pump is as follows: The inlet port l6 and the outlet port iii are connected to suitable conduits and the power source (not shown) is energized, rotating the shaft 16.

,The wheel 15 is thereby set in rotation and the acentric mounting of the ball bearing 18 causes the wobble stick 64 to gyrate on the ball 38. This gyration causes the wobble plate 81 to wobble. from one extreme position to the other and back again for each cycle of gyration of the wobble stick 64. The rods 18 move with the wobble plate 69 and push and pull on the pistons 54.

When the pistons 54 are moved toward left, they are on the suction stroke. During the suction stroke the head valve pad 13a seals off the upper end of the cylinder 51 and the void that is created causes the piston valve 59 to move against the tension of the spring 6i and lift off of its conical seat 58. The fluid being pumped (either gaseous or liquid) flows from the inlet l8 through the aperture 33 into the left end of the piston 54 and fills the space between the right end of the piston and the head valve pad 13a. When end of its suction stroke, the suction pressure is neutralized and the piston valve 58 closes. The pumping fluid is then trapped between the piston 54 and the head valve p d Ila.

Movement of the pistons toward the right Gives rise to the pumping stroke and the trapped fluid is then compressed. When the spring pressure and back pressure are overcome, the head valve 13, 13a opens. The fluid then enters the cap 45 and the high pressure region of the bore 43.- When the piston 54 reaches the end of its pumping stroke (lower piston of Fig. l), the 'end of the piston and its valve are flush with the end of the cylinder 46. The head valve 13, 13a then closes, and the piston starts its suction stroke as previously described.

The high pressure fluid then passes about the bore l3 to the passage 2i and thence to the outlet port l8 for utilization in any desired fashion. The pump being a positive displacement pump, however, continues to supply high pressure fluid regardless of utilization of the fluid. If the fluid is not utilized sufllciently rapidly, an excessive back pressure may be developed that would injure the pump or the associated control valves. This pressure is transmitted through the passage ii! to the relief bore ll. When the pressure ex-' ceeds the compression of spring 3| and the exhaust back pressure, the relief valve 28-29 opens, venting the excessive pressure to inlet pressure.

The entire left portion of the pump, except for the relief portion II, is open to inlet fluid to permit free access of this fluid to the pistons 54. Since this inlet pressure is usually less than atmospheric pressure, the atmospheric pressure forces the tubular bag to the left as shown, pulling on its terminal heads to assume the desired position for free movement of the wobble stick 54. If the inlet pressure exceeds atmospheric, an appropriate conical spring may be provided having its smaller end secured to the wobble stick 64 and its larger end contact the fold of the tube 80.

It will be noted that the inlet valve not only acts as a part of the piston, but that its upper surface is flush with the end of the piston. This construction permits the elimination of volume at the end of the pumping stroke as indicated with the lower piston of Fig. 1. This renders the pump ideal for pumping gases in that all gas is expelled at the end of the pumping stroke, resulting in a stronger suction action on the subsequent suction stroke.

The pump housing I0 being machined with a series of concentric bores allows the principal machining operations to be performed with one setting of the housing. Further, the various chambers are simply formed by sealing off the various bores with donut or O-ring seals that are standard in the aircraft industry. These construction simplifications make possible the efficient manufacture of small pumps, and one manufactured embodiment has smaller dimensions than the drawing of this specification. The eflicient driving mechanism eliminates frictional losses.

Although my invention has been described with reference to particular embodiments thereof, it is not limited to these embodiments nor otherwise, except by the terms of the following claim.

I claim:

In a wobble plate pump, a working cylinder, a head valve normally sealing one end of the cylinder, a tubular piston placed in the cylinder and having a valve seat formed on the end toward the head valve, an inlet valve positioned on the valve seat and so shaped with respect to the piston end and the head valve that no voids exist when the piston is at the extreme of its stroke toward the head valve, and wobble plate means for reciprocating the piston in the cylinder.

ALEX BERTEA.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Banning June 7, 1927 Banning June 4, 1929 Richer Jan 26, 1932 FOREIGN PATENTS Country Date France 1914 

